Use compression lib to gzip files

I added the gzip compress to the Express 4.x server by using the `compression` :hammer: library.

_NOTE: Remember to run `npm install` to ensure that the compression library is downloaded._

![screen shot 2014-08-06 at 12 38 32 am](https://cloud.githubusercontent.com/assets/28176/3822688/533fda86-1d2c-11e4-81bb-ecc8b934cfe2.png)
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![screen shot 2014-08-06 at 12 39 20 am](https://cloud.githubusercontent.com/assets/28176/3822689/56b0e4e4-1d2c-11e4-87d0-a8d158b6c993.png)


Fixes #24 @imalooney